Inside the Mysterious Life of Detroit Boy Found in Basement

The missing 12-year-old boy who mysteriously turned up in his own basement was home-schooled, subjected to an intense exercise regimen, and was possibly abused, police said.

As new details emerged about the strange case, authorities are painting a picture of what life was like for Charlie Bothuell V. He was found Wednesday in the basement of the condo building where he lives with his father and stepmother near downtown Detroit, 12 days after his father reported him missing.

Bothuell was found barricaded behind a 55-gallon barrel, surrounded by bedding, soda bottles and cereal, police said. They also said they found a blood-stained PVC pipe in the home.

"He indicated he was hungry, but he seemed to be both nervous and excited," a police officer told ABC News.

They do not know how long the boy had been in the basement, but don't believe he was there the entire time he was missing. Police had previously searched the home four times, once with a cadaver dog.

HLN's Nancy Grace interviewed the boy's father, Charlie Bothuell IV, before he knew his son had been found. Grace broke the news that the boy had been found unharmed to Bothuell on live TV, presumably shocking the father, who is now being investigated by police as a person of interest in the case.

Grace shed light on the boy's reported strict exercise regimen on "Good Morning America" today, saying he was forced to walk 4,000 steps daily on an elliptical machine. Bothuell had told police that his son disappeared after a 9 p.m. workout.

Grace explained how, just before her interview, Bothuell received a text message from his wife -- the boy's stepmother, showing a photo of the elliptical and stating, "Charlie's not doing his chores."

Bothuell, who home-schools his son, may have told his son the family was going to move in the fall, which could have caused the boy to run away, Grace said.

Police said they are investigating the case as possible case of child abuse, and they are also questioning the stepmother, Monique Dillard-Bothuell.

She was taken into custody on Thursday for an unrelated case, police said. She was charged with violating probation for an earlier weapons charge and remains in custody, according to jail records.

The boy passed a medical exam and is now in the custody of his biological mother, authorities said.